1. Field of the Invention (Technical Field)
The present invention relates to luggage, particularly wheeled luggage, and specifically a stable, easily pushed or pulled, two-wheeled luggage case. More particularly, the present invention relates to luggage cases formed of substantially two parts, the first part of a generally one-piece molded plastic construction, the other of a composite construction primarily of textile fabric panels assembled to form a covering that includes an access lid to the interior of the first molded part.
2. Background Art
Generally, luggage cases fall into two basic categories of construction. The first, generally called "hardside", comprises luggage cases made of thermoplastic or composite materials forming a generally box shape, the sides of the box having a generally rigid, resilient construction. Such hardside cases are now generally made of thermoplastic materials, having large portions of the luggage case formed of one piece in an injection molding or vacuum forming process. Other hardside cases have been formed of paperboard or metal sheet materials held together with edge trim and corner hardware to form a box. These boxes, whether formed of parts or integrally, are generally comprised of a lid shell hinged to a base shell.
Another form of luggage construction incorporates large portions of the hardside construction together with almost equal shares of softside construction. This type of luggage is generally shown in U.S. Pat. No. 5,447,261 which published patent is hereby incorporated by reference. The '261 patent could be generally characterized as an upright style case having a handle 36 at one end of its elongated dimension and a pair of wheels 28 at the other end. This luggage case has a one-piece base box 12 integrally formed of plastics material. The other portion of the case is a bag or cover 16 which closes the opening 14 to the inside of the base box 12. The cover 16 is stapled or stitched to the upper edge of the box 12. A slide fastener runs around the perimeter of the joint between the overlapping portion of the cover 16 to permit access to the space defined by the lid 16 and the box 12.
However, Applicants have found that properly fitting a generally textile constructed lid to the integrally molded sides of a base shell is difficult. This is especially true with a large case, and most especially where the lid shell is constructed at a location remote from where the lid and base shell are joined to integrate the two and form the overall luggage case.
For example, sewing a textile lid or cover around the periphery of the walls of a molded base shell can create gaps and mismatches between the adjacent textile and molded portions. The foot of a typical sewing machine can cause the textile material to creep or walk ahead of the sewing operation, resulting in a large amount of textile material in the lid to accumulate or gather ahead of the stitch line. Also, even if the textile portion and the molded portions exactly dimensionally matched one another initially, this could change with humidity, especially if the textile portion was constructed of a polyamide or nylon textile materials. It is well know that nylon can take on moisture, causing the overall dimensions of the textile panels to grow a substantial amount.
The luggage case constructed in accordance with U.S. Pat. No. 5,447,261 is known to include slots arranged at right angles in the edge of the box 12 at each comer radius. These slots are suspected to permit the outside circumference of this edge portion of the box to compress slightly to accommodate the dimensional variations or differences between the box edge and the corresponding edge of the cover 16.
Also, the joint between the lid and base shell is quite critical to the overall strength of such a hybrid between textile construction and an integrally molded base construction. A luggage case can suffer from extremes of heat and cold, and is often severely abused during its useful life. The cavity defined inside the luggage case can be filled with the traveler's things will likely weigh many times the empty weight of the luggage case. This weight puts great stresses on the luggage case, called "burst" forces, which tend to split the case apart. It is well recognized that the joints or seams in a typical textile constructed luggage case can be the weak points with regard to resisting such burst forces. However, the joint between the generally rigid base shell in the hybrid case and the textile lid or cover may be even more vulnerable to bursting, since the differences in rigidities between the two case portions will cause a stress concentration at the joint.
Also, the peripheral joint between the rigid base shell and a textile lid shell presents an opportune location for carrying straps and fasteners. A construction which permits locating and attaching these auxiliary straps and handles would present an ideal integration of the lid and base shell and these points of attachment, while distributing the stress inherent in the use of these handles and straps into the joint construction.